Avid - MTB Brake Squeeeeeeel!

[Four Litre]

My Trek Fuel Ex8 is fitted with OEM Avid brakes and as time goes by the brakes squeal more and more and then some. Its got to the level now that it does it on every rotation of the wheel. I recently paid for a service and to have them looked at, now there even worse. I even resorted to spraying them with silicone today as I would rather have no brakes that the noise they make. After 10 mins riding it came back.....HELP

[Four Litre]

Thanks fo the info - will give it a go. The front squeak on every rotaion of the wheel - they both squeal very load when used!

The bike shop said Avid brakes were very hard to setup - didnt know whether this was an excuse or...